I am digging into this issue trying to get the SARA 410M module back alive.I do have the rev3 board which has an additional onboard usb connection. When I connect this to my computer this port is installed as a new COM port. I used the arduino serial montor to see what happens. If I send something I get some spaces and a 0 (zero)

2nd thing I was digging into is the boot-pin Monalisan mentioned above. I am not sure which pin I need to use. Is it the SARA_R4XX_TOGGLE pin which is defined into the board definition?